503 research outputs found
Compactness of moduli spaces for orbifold instantons
AbstractMany questions related to 3- and 4-dimensional topology can be expressed in terms of certain singular spaces dubbed ‘pseudofree orbifolds’. A successful technique for studying these spaces is to examine the moduli spaces of self-dual connections on (orbifold) bundles over them, and a theorem of Fintushel and Stern shows that these moduli spaces must be compact when the corresponding bundle has small enough Pontryagin number. The purpose of this article is to show how this compactness range can be considerably extended for purely equivariant topological reasons
Sex roles in social movements: a case study of the tenant movement in New York City
Publisher's version/PDFMany recent studies have documented the presence of sexism in American society, charted the oppressive impact of discrimination against women, and traced its sources. So ubiquitous is sexism, and so pervasive the engines supporting it, that, ironically, its trace may be found even within movements for social justice. A literature is now developing that describes the part women have played in social movements and the sexism they encountered there. This is largely descriptive, focusing on the ideological interchange between party leadership and feminists
Engaging Low-Income Parents in Childhood Obesity Prevention from Start to Finish: A Case Study
Prevention of childhood obesity is a national priority. Parents influence young children’s healthy lifestyles, so it is paradoxical that obesity interventions focus primarily on children. Evidence and theory suggest that including parents in interventions offers promise for effective childhood obesity prevention. This case study engaged parents’ as co-researchers in the design, implementation and evaluation of an intervention for low-income families with a child enrolled in Head Start. Parent engagement mechanisms include: (1) targeted partnership development (2) operationalizing a Community Advisory Board (CAB) that was the key decision making body; (3) a majority of CAB members were parents who were positioned as experts, and (4) addressing structural barriers to parent participation. Lessons learned are provided for future research, and practice
Formal Alliances, 1816-1965: an Extension of the Basic Data
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69121/2/10.1177_002234336900600305.pd
Genomic Tools for Evolution and Conservation in the Chimpanzee: Pan troglodytes ellioti Is a Genetically Distinct Population
In spite of its evolutionary significance and conservation importance, the population structure of the common chimpanzee, Pan troglodytes, is still poorly understood. An issue of particular controversy is whether the proposed fourth subspecies of chimpanzee, Pan troglodytes ellioti, from parts of Nigeria and Cameroon, is genetically distinct. Although modern high-throughput SNP genotyping has had a major impact on our understanding of human population structure and demographic history, its application to ecological, demographic, or conservation questions in non-human species has been extremely limited. Here we apply these tools to chimpanzee population structure, using ∼700 autosomal SNPs derived from chimpanzee genomic data and a further ∼100 SNPs from targeted re-sequencing. We demonstrate conclusively the existence of P. t. ellioti as a genetically distinct subgroup. We show that there is clear differentiation between the verus, troglodytes, and ellioti populations at the SNP and haplotype level, on a scale that is greater than that separating continental human populations. Further, we show that only a small set of SNPs (10–20) is needed to successfully assign individuals to these populations. Tellingly, use of only mitochondrial DNA variation to classify individuals is erroneous in 4 of 54 cases, reinforcing the dangers of basing demographic inference on a single locus and implying that the demographic history of the species is more complicated than that suggested analyses based solely on mtDNA. In this study we demonstrate the feasibility of developing economical and robust tests of individual chimpanzee origin as well as in-depth studies of population structure. These findings have important implications for conservation strategies and our understanding of the evolution of chimpanzees. They also act as a proof-of-principle for the use of cheap high-throughput genomic methods for ecological questions
MiRNA Control of Vegetative Phase Change in Trees
After germination, plants enter juvenile vegetative phase and then transition to an adult vegetative phase before producing reproductive structures. The character and timing of the juvenile-to-adult transition vary widely between species. In annual plants, this transition occurs soon after germination and usually involves relatively minor morphological changes, whereas in trees and other perennial woody plants it occurs after months or years and can involve major changes in shoot architecture. Whether this transition is controlled by the same mechanism in annual and perennial plants is unknown. In the annual forb Arabidopsis thaliana and in maize (Zea mays), vegetative phase change is controlled by the sequential activity of microRNAs miR156 and miR172. miR156 is highly abundant in seedlings and decreases during the juvenile-to-adult transition, while miR172 has an opposite expression pattern. We observed similar changes in the expression of these genes in woody species with highly differentiated, well-characterized juvenile and adult phases (Acacia confusa, Acacia colei, Eucalyptus globulus, Hedera helix, Quercus acutissima), as well as in the tree Populus x canadensis, where vegetative phase change is marked by relatively minor changes in leaf morphology and internode length. Overexpression of miR156 in transgenic P. x canadensis reduced the expression of miR156-targeted SPL genes and miR172, and it drastically prolonged the juvenile phase. Our results indicate that miR156 is an evolutionarily conserved regulator of vegetative phase change in both annual herbaceous plants and perennial trees
Effect of Dietary Zinc Oxide on Morphological Characteristics, Mucin Composition and Gene Expression in the Colon of Weaned Piglets
The trace element zinc is often used in the diet of weaned piglets, as high
doses have resulted in positive effects on intestinal health. However, the
majority of previous studies evaluated zinc supplementations for a short
period only and focused on the small intestine. The hypothesis of the present
study was that low, medium and high levels of dietary zinc (57, 164 and 2,425
mg Zn/kg from zinc oxide) would affect colonic morphology and innate host
defense mechanisms across 4 weeks post-weaning. Histological examinations were
conducted regarding the colonic morphology and neutral, acidic, sialylated and
sulphated mucins. The mRNA expression levels of mucin (MUC) 1, 2, 13, 20,
toll-like receptor (TLR) 2, 4, interleukin (IL)-1β, 8, 10, interferon-γ
(IFN-γ) and transforming growth factor-β (TGF-β) were also measured. The
colonic crypt area increased in an age-depending manner, and the greatest area
was found with medium concentration of dietary zinc. With the high
concentration of dietary zinc, the number of goblet cells containing mixed
neutral-acidic mucins and total mucins increased. Sialomucin containing goblet
cells increased age-dependently. The expression of MUC2 increased with age and
reached the highest level at 47 days of age. The expression levels of TLR2 and
4 decreased with age. The mRNA expression of TLR4 and the pro-inflammatory
cytokine IL-8 were down-regulated with high dietary zinc treatment, while
piglets fed with medium dietary zinc had the highest expression. It is
concluded that dietary zinc level had a clear impact on colonic morphology,
mucin profiles and immunological traits in piglets after weaning. Those
changes might support local defense mechanisms and affect colonic physiology
and contribute to the reported reduction of post-weaning diarrhea
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